The present application claims priority under 35 U.S.C. 119 of Japanese Patent Application No. 2001-219324 filed on Jul. 19, 2001, the entire contents thereof being hereby incorporated by reference.
1. Field of the Invention
This invention relates to an engine mount structure for a personal watercraft. More particularly, the present invention relates to an engine mount structure for a personal watercraft wherein an engine for driving a jet propulsion pump is incorporated in a body having a hull and a deck.
2. Description of Background Art
Conventionally, a two-cycle engine is incorporated in personal watercraft that are in widespread use. The engine is disposed in such a posture that a cylinder thereof stands substantially upright at the center of the body of the watercraft.
In recent years, interest in using a four-cycle engine in a personal watercraft has been increasing because of the benefits of reducing exhaust gas pollution and noise.
However, since the four-cycle engine has a greater overall engine height when compared with the two-cycle engine, because of the structure of the cylinder head, even if the cylinder capacity is equal, it is difficult to incorporate the four-cycle engine in a small body of a personal watercraft in such a posture that the cylinder thereof stands substantially upright.
Thus, a personal watercraft has already been proposed wherein a 4-cycle engine is incorporated in a body in such a state wherein it is inclined to one side around the crankshaft thereof (the official gazette of Japanese Patent Laid-Open No. Hei 10-252440).
Usually, an engine has an upper case and a lower case joined along a transverse plane parallel to the crankshaft of the engine. However, in a conventional engine, a mount portion thereof is provided, both at the left and the right thereof, on the lower case.
Therefore, there is a problem that, if the engine (particularly a four-cycle engine) is installed in the body in a state wherein it is inclined to one side about the crankshaft thereof, then it is difficult to mount the engine in a well-balanced state in the body, or the mount portion (for example, a mount arm portion) must have an increased size, which uses small and precious space in the body and makes it difficult to arrange parts of ancillary mechanisms or parts for the intake and exhaust systems.
An object of the present invention resides in solution of such a problem as described above to provide an engine mount structure for a personal watercraft by which an engine can be incorporated in a well-balanced state in a body and the space in the body can be utilized efficiently.
In order to attain the object of the invention described above, an engine mount structure for a personal watercraft is provided wherein an engine for driving a jet propulsion pump is incorporated in the inside of a watercraft body having a hull and a deck, and the engine has an upper case and a lower case which are joined along a transverse plane parallel to a crankshaft of the engine. The engine is mounted in a state wherein the engine is inclined to one side about the crankshaft, and mount portions of the engine that attach to the body are provided at the left and the right of the engine on the upper case and the lower case.
To attain another object of the invention, the engine mount structure for a personal watercraft allows the engine to be mounted in an inclined relationship such that an intake port side is positioned on the upper side thereof while an exhaust port side is positioned on the lower side thereof, and the mount portions provided on the intake port side are provided on the lower case while the mount portions on the exhaust port side are provided on the upper case.
To attain another object of the invention, the engine mount structure for a personal watercraft is used with an engine provided with a supercharger, and an intercooler connected to the supercharger and a surge tank are connected to the intake port.
To attain another object of the invention, the engine mount structure for a personal watercraft is used with an engine having a starter motor for starting the engine attached to the upper case, and the mount portions on the side to which the starter motor is attached are provided on the lower case.
With the inventive engine mount structure for a personal watercraft, the engine for driving the jet propulsion pump is incorporated in the watercraft body surrounded by the hull and the deck. The engine has the upper case and the lower case joined along a transverse plane parallel to the crankshaft of the engine and is mounted in a state wherein it is inclined to one side about the crankshaft. Mount portions of the engine that attach to the body are provided at the left and right sides of the engine on the upper case and the lower case, whereby the engine can be incorporated in a well-balanced condition in the body in an attitude inclined to one side about the crankshaft thereof.
Further, since the mount portions can be made compact, ancillary mechanisms or parts for the intake and exhaust systems can be disposed utilizing the small and precious intra-body space effectively.
Also, with the inventive engine mount structure for a personal watercraft, the engine is mounted in an inclined state such that the intake port side thereof is positioned on the upper side and the exhaust port side thereof is positioned on the lower side. The mount portions on the intake port side are provided on the lower case and the mount portions on the exhaust port side are provided on the upper case, whereby the space above the mount portions on the lower case side is wide and equipments for the intake system or a member can be disposed to make effective use of the space.
Particularly where the engine is an engine with a supercharger and the intercooler connected to the supercharger and the surge tank are connected to the intake port of the engine, the intercooler and the surge tank can be accommodated in the wide space above the mount portions on the lower case side. Accordingly, such an engine mount structure is particularly effective where the engine is provided with a supercharger.
With the inventive engine mount structure for a personal watercraft, the starter motor for starting the engine is provided on the upper case and the mount portions on the side on which the starter motor is mounted are provided on the lower case. Consequently, the starter motor can be disposed near the engine without interfering with the mount portions, and the engine weight including the starter motor can be concentrated in the proximity of a central portion of the watercraft body, and the cornering performance of the boat can be enhanced.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.